Allow a flag to convert ASCII DEL into Backspace

t/20canon.c

@@ -9,7 +9,7 @@ int main(int argc, char *argv[])
 
 #define CLEAR_KEY do { key.type = -1; key.code.codepoint = -1; key.modifiers = -1; key.utf8[0] = 0; } while(0)
 
-  plan_tests(18);
+  plan_tests(26);
 
   tk = termkey_new(0, TERMKEY_FLAG_NOTERMIOS);
 
@@ -45,6 +45,22 @@ int main(int argc, char *argv[])
   is_int(key.modifiers, 0,                   "key.modifiers for Space/symbol");
   is_str(endp, "", "consumed entire input for Space/symbol");
 
+  CLEAR_KEY;
+  endp = termkey_strpkey(tk, "DEL", &key, 0);
+  is_int(key.type,      TERMKEY_TYPE_KEYSYM, "key.type for Del/unconverted");
+  is_int(key.code.sym,  TERMKEY_SYM_DEL,     "key.code.codepoint for Del/unconverted");
+  is_int(key.modifiers, 0,                   "key.modifiers for Del/unconverted");
+  is_str(endp, "", "consumed entire input for Del/unconverted");
+
+  termkey_set_canonflags(tk, termkey_get_canonflags(tk) | TERMKEY_CANON_DELBS);
+
+  CLEAR_KEY;
+  endp = termkey_strpkey(tk, "DEL", &key, 0);
+  is_int(key.type,      TERMKEY_TYPE_KEYSYM,   "key.type for Del/as-backspace");
+  is_int(key.code.sym,  TERMKEY_SYM_BACKSPACE, "key.code.codepoint for Del/as-backspace");
+  is_int(key.modifiers, 0,                     "key.modifiers for Del/as-backspace");
+  is_str(endp, "", "consumed entire input for Del/as-backspace");
+
   termkey_destroy(tk);
 
   return exit_status();

termkey.c

@@ -610,6 +610,12 @@ void termkey_canonicalise(TermKey *tk, TermKeyKey *key)
       fill_utf8(key);
     }
   }
+
+  if(flags & TERMKEY_CANON_DELBS) {
+    if(key->type == TERMKEY_TYPE_KEYSYM && key->code.sym == TERMKEY_SYM_DEL) {
+      key->code.sym = TERMKEY_SYM_BACKSPACE;
+    }
+  }
 }
 
 static TermKeyResult peekkey(TermKey *tk, TermKeyKey *key, int force, size_t *nbytep)

termkey.h.in

@@ -151,6 +151,7 @@ enum {
 
 enum {
   TERMKEY_CANON_SPACESYMBOL = 1 << 0, // Space is symbolic rather than Unicode
+  TERMKEY_CANON_DELBS       = 1 << 1, // Del is converted to Backspace
 };
 
 void termkey_check_version(int major, int minor);

termkey_canonicalise.3

@@ -16,6 +16,9 @@ The canonicalisation operation is affected by the following flags:
 .TP
 .B TERMKEY_CANON_SPACESYMBOL
 If this flag is set then a Unicode space character is represented using the \fBTERMKEY_SYM_SPACE\fP symbol. If this flag is not set, it is represented by the U+0020 Unicode codepoint.
+.TP
+.B TERMKEY_CANON_DELBS
+If this flag is set then an ASCII DEL character is represented by the \fBTERMKEY_SYM_BACKSPACE\fP symbol. If not, it is represented by \fBTERMKEY_SYM_DEL\fP. An ASCII BS character is always represented by \fBTERMKEY_SYM_BACKSPACE\fP, regardless of this flag.
 .SH "RETURN VALUE"
 \fBtermkey_canonicalise\fP() returns no value.
 .SH "SEE ALSO"